Thermal diffusivity of proton and spallation neutron irradiated - - PowerPoint PPT Presentation

Tungsten R&D at ESS

Thermal diffusivity of proton and spallation neutron irradiated tungsten

Jemila Habainy1,2 Yongjoong Lee1, Yong Dai3, Srinivasan Iyengar1,2 European Spallation Source1, Lund University2 , Paul Scherrer Institut3

7th High Power Targetry Workshop, East Lansing, Michigan, June 2018

ESS Tungsten Target

dpa/year in Tungsten

• 2.5 m diameter, rotating, helium-cooled, 7000 pure tungsten bricks, 8x3x1 cm3
• 5 MW, 2.0 GeV, 14 Hz pulsed proton beam 
• 357 kJ/pulse deposited in target,  100 C/pulse, max. temp 450 C, max. stress 100 MPa
• Accumulated damage max. 2 dpa/year (5-year lifetime)
• Potential issues:

Degradation of thermal and mechanical properties, severe irradiation-induced embrittlement, fatigue, oxidation,

36 sectors

2

Image by ESS-Bilbao

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

• Unirr. tungsten – Fatigue studies
• Ramp up and normal beam pulses will cause thermal fatigue
• Fatigue and tensile tests were conducted at 25°, 280° and 480°C
• Comparing fatigue limits of rolled, forged and HIPed tungsten, from 4

different suppliers

–

• J. Habainy et al. Fatigue behaviour of rolled and forged tungsten at 25°, 280° and 480

°C, J. Nucl. Mater., vol. 465, pp. 438-447, 2015 –

• J. Habainy et al. Fatigue properties of tungsten from two different processing routes,
• J. Nucl. Mater., vol. 506, pp. 83-91, 2018

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

3

• Unirr. tungsten – Fatigue studies

Ductile to brittle transition temperature is high, some specimens are still completely brittle at 500°C

HIPed Rolled 25 °C 480 °C 480 °C 280 °C

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

4

PSI: SINQ Target Irradiation Program – STIP V

5

560 MeV/ 1.3 mA Proton beam

• STIP-V Irradiated between 2007-2008
• 560 MeV/ 1.3 mA proton beam
• 2x hot-rolled W bars, size: 60x8x1mm
• 5-28 dpa, 100°-800 °C

STIP-V irradiated tungsten

Rod 3 Rod 5

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Two low dose samples: 3.9 dpa, 158 appm He, Tirr 115 °C 5.8 dpa, 245 appm He, Tirr 140 °C

with approx. 2% Rhenium

8

Jemila Habainy

LFA at PSI

LFA – Light Flash Apparatus

9

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Thermal conductivity = Thermal diffusivity  Specific heat  Density Thermal diffusivity = 0.1388  d2 t1/2

https://www.netzsch-thermal-analysis.com/en/landing- pages/principle-of-the-lfa-method/

Thermal diffusivity – unirradiated

10

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Effect of surface preparation

11

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Akiyoshi, M., Fusion Engineering and Design (2018), https://doi.org/10.1016/j.fusengdes.2018.03.008

12

13

Thermal diffusivity – irradiated

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Effect of rhenium content on thermal diffusivity of unirradiated tungsten

14

• T. Tanabe et al. / Materials Letters 57 (2003) 2950–

2953

Unirradiated

• F. Hofmann et al. / Scientific Reports volume 5, Article number: 16042

(2015)

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

15

W and W-Re alloys (up to 25 mass % Re) were irradiated in the Japan materials test reactor (JMTR) reactor at 330 K to thermal and fast neutron fluences of 1.031020and 3.371019 (E> 1 MeV), respectively.

Effect of rhenium content on thermal diffusivity of neutron irradiated tungsten

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

16

Effect of rhenium content on thermal diffusivity of neutron irradiated tungsten

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018 0.88 0.92 0.96 1 1E+11 1E+12 1E+13 1E+14 Thermal diffusivity Fluence [ions/cm2] Normalised thermal diffusivity of gold

ion irradiated tungsten

Heavy ion irradiated tungsten foil

Thermal diffusivity of annealed irradiated tungsten

17

Annealed at 1000 C, 1 h

Jemila Habainy  7th High Power Targetry Workshop  East Lansing, Michigan  June 2018

Simulating temperature in ESS tungsten using LFA results

18

Standard material data LFA material data (irr W) Simulation model Temperature [C] in ESS tungsten immediately after a pulse

Simulating stress in ESS tungsten using LFA results

19

Standard material data LFA material data LFA material data + 20 % increase in stiffness Equivalent stress in ESS tungsten immediately after a pulse

83 MPa  117 MPa

20

20 mm

• Unirr. tested at 450°C

1.4 dpa, tested at 450°C

Summary

Studies of thermal and mechanical properties of irradiated tungsten: Thermal diffusivity – decreased by 28-51% lower, depending on

• temperature. Annealing of 3.9 dpa W, at 1000 °C for 1 h, resulted in

a slight recovery of thermal diffusivity. Fatigue – lowest runout at 135 MPa. Rolled tungsten has higher fatigue limit but shows more scatter. Hardness – increased by almost 75 % at 3.5 dpa Ductility – tungsten shows zero ductility at ESS relevant temp., already at 1.3 dpa Oxidation – even 5 ppm impurity in He will oxidize tungsten

21